Metal working lubricant



United States Patent 3,124,531 METAL WORKING LUBRICANT Joshua C.Whetzel, Jr., Fox Chapel, and Sayre Rodman, Oakmont, Pa., assignors toFar-Best Corporation, Los Angeles, Calif, a corporation of California gNo Drawing. 'Filed Oct. 28, 1959, Ser. No. 849,147

- 4 Claims. (Cl. 25252) This invention relates to improved lubricantsfor use in Working metal as by rolling, drawing or forging aluminum orother metal and is described herein particularly as applied to therolling of aluminum sheets and foil.

While rolling aluminum and aluminum alloys to produce sheet or foil,lubricants are used to decrease friction between the metal and rolls ofthe rolling mill and to promote good surface finish. These lubricantsalso serve as heat transfer fluids to remove heat generated in the rollsand metal during rolling. In addition to the above uses, lubricantsshould be compounded so as to minimize stain on the surface of the metalduring anneal cycles or in storage. These lubricants should be non-toxicto mill personnel in use and also non-toxic to subsequent users of themetal if residual films of lubricant remain on the metal surface.Further, these lubricants should not possess objectionable odors andthey should satisfy the usual criteria of availability and economy.

Lubricants used for rolling of aluminum are almost always mixtures ofpolar or oiliness additives with light mineral or hydrocarbon oils ordistillates.

I The additives employed for aluminum rolling are generally fats, suchas palm oil or lanolin, or other esters of fatty acids,, such as butylstearate. The purpose of these additives is to provide the light mineraloil or mineral distillate with more oiliness or boundary lubricatingability than it would otherwise possess. Generally, these fatty esters,being closely related chemically, all work in about the same way. Theyshow characteristic relationships between concentration in a lubricantand resultant effects.

The effect of additives in rolling lubricants is to improve thelubricating ability of the oil, thus decreasing friction in the rollbite between rolls and metal. By resultant effects, a decrease infriction allows greater and more eflicient reduction in thickness of themetal being rolled. These additives also, through their chemical orpolar action, serve to decrease the tendency of the metal to weld to orpick up on the surface of the rolls during rolling.

For most rolling jobs, the concentration of additive in the lightpetroleum oil or distillate will range from 1 to about At intermediatestages in the manufacture of aluminum sheet or foil, the rolled stripmetal must be annealed or heat treated to soften its structure. In amajority of cases, probably, the final manufacturing step beforeshipment will be an annealing treatment. The typical heat treatingcycles demand that the metal be heated for a period of time attemperatures ranging from about 650 F. to about 900 F., usually in aninert atmosphere. Because of industrypractices, the rolling lubricant isallowed to remain ice on the metal surface during this operation. Thus,careful attention must be given to the tendencies of both additive andbase oil to form residues as a result of such heating. These residueswhich commonly occur to a minor extent are called stains" and appear onthe metal surface as a discoloration, marring the luster and value ofthe product.

Of prime importance in considering the staining tendencies of apotential additive or base oil is the boiling range of these materialsand their heat degradation (cracking or polymerization) behavior inatmospheres of the type found in annealing furnaces.

The vehicle used for rolling, light mineral or petroleumderived lightoils and distillates, will vary in viscosity in usual work from about 30to about 60 Saybolt seconds, universal, at F. The choice of viscosityfor a particular rolling job will vary with the particular requirements.Reduction per pass, assuming equivalent rolling loads and equivalentadditive concentration, normally increases with increasing oilviscosity. Capacity of a lubricant to remove heat from the rolls andmetal will vary inversely with increasing viscosity. Also, finish orluster of the rolled metal is somewhat dependent upon the viscosity ofthe lubricant used in rolling, so long as other factors, unrelated tolubrication, remain equal. And, in addition, the amount or degree ofstain remaining on the rolled product after annealing will vary directlywith oil viscosity and boiling range.

Therefore, to provide the desired properties and necessary requirementsin particular cases of rolling, we find relatively well definedlubricants in general use. For heavier so-called sheet gauges or onbreakdown mills rolling sheet destined for lighter gauges, light mineraloils with viscosities of about 38 to 45 Saybolt seconds, universal, at100 F., are used compounded with about 1 to 5% of fatty oils or fattyacid esters. In the manufacture of light gauge aluminum sheet and foil,close control of roll temperature is necessary to control roll shape andthus good heat transfer fluids are needed. This requirement dictates theuse of lighter distillates, such as kerosene, in the viscosity range of30 to 35 Saybolt seconds, universal, at 100 F. Also, in suchapplication, less reduction is often taken and, at the same time,luster, finish and stain requirements are very strict. All of therequirements dictate the use of light distillates, such as kerosene,usually compounded with 5% or less of fatty oils or fatty acid esters.

An object of our invention is to provide a more useful additive than hasbeen known previously for use in light mineral oils and distillates toform a lubricant for metal working, particularly to lubricate therolling of aluminum sheet and foil.

We havefound that the combination of fatty alcohols of the generalformula R-OH, where. R is a straight paraifinic chain of from 10 to 20carbon atoms, either saturated or partially unsaturated, andpolypropylene glycols of the general formula HO-CH CHCH O--CH CHCH OHand average molecular weight ranging from 134 through 4000, possessunexpected excellent properties as additives for rolling aluminum sheetand foil when dissolved in light petroleum oils and distillates havingviscosities ranging between 30 and 80 Saybolt seconds, universal, at 100The lower members or the polypropylene glycol series (below 750 averagemolecular weight) are almost completely insoluble in the usual lightmineral oils and distillates used for rolling aluminum. One of thepurposes F., the viscosity preferably being between 30 and 60 Sayof thefatty alcohol in the mixture is to provide a coupling bolt seconds,universal, at 100 F. action, thus providing mutual solubility of theglycol and Fatty alcohols are produced by high pressure catalyticmineral oil. hydrogenation or sodium reduction of fatty acids or fattyTypical compositions according to the invention are acid esters derivedfrom fats. The commercial grades of given in Table 1.

Table 1 [Components, parts per 100, by weight] Composition No 1 2 3 4 56 7 8 9 10 11 12 13 14 15 16 17 1s 19 20 Name of Component:

00ml. Lauryl Ale 3 Coml. Oleyl Alc. Tallow Alcohol 3. 95 3.825 3. 05 3.32. 6 3 12 1. 5 .75 Dipropylene Glycol.. 1 Polypropylene Glycol 150. .05.175 .35 0.7 .5 .25 Polypropylene Glycol 425. Polypropylene Glycol 1025Polypropylene Glyc0l3000 Kerosene, 31 SUS, 100 F Light Mid. Oil, 37SUS,100 F. 90 96 96 96 96 96 9e 90 84 92 9s 09 Light Min. Oil, 58 SUS,100 F 96 fatty alcohols are mixtures of several different alcohols,reflecting the mixtures of fatty acids in the fat from which they werederived. Thus, in the terminology of these materials, we have mixturesknown as coconut or tal- The mixtures of fatty alcohols andpolypropylene glycols of our invention are unique in that thecombination of the materials is a better lubricant than equivalentconcentrations of either the fatty alcohols or the polypropylene glycolsalone. The following Table 2 illustrates this phenomenon. The data wereobtained under actual rolling conditions, rolling aluminum strip of thethickness indicated on a rolling mill equipped with instruments formeasuring rolling loads. The comparative figures given are reductions inthickness of the strip, in one pass, at constant rolling load, asindicated. Reduction under these conditions is a direct function ofdecrease in friction caused by the lubricant.

Table 2 COMPOSITION, BY TYPE OF ALCOHOL, PERCENT Chain Coml. 00ml. Coml.Alcohol Length, Lauryl Oleyl allow Carbon Ale. Ale. Ale. Atoms YArachidonyl the highest member of the homologous series now incommercial production. Typical specifications of a few members of thisseries follow:

AVERAGE MOLECULAR WEIGHT Specific Gravity, 20/20 C 1. 0245 1. 0114 1.004 1.0070 1.001 (25C) (25C) Viscosity, Centistokes,

210 F 3. 0 4. 5 7.8 10. 9 50.9 Flash Point, F 250 385 495 420 440Solubility in Water, 20 0,

percent 0. 2 0.1 Solubility in Heptane, 20 0,

percent 1 Complete. 2 Insoluble.

Reduction, percent of .005

Rolling Load 5500 lbs. per in. of Strip Width 64 64 65 Comp. N0. 16 64 4parts Polyprop. Gly. 1025, parts Light Min. Oil, 37 SUS 59 4 partsPolyprop. Gly. 3000 in 96 parts Same Oil 61 4 ;())arts Tallow Alcohol in96 parts Same Oil 58 4 parts Palm Oil, 96 parts Same 58 4 parts Lanolin,96 parts Same Oi 59 Light Mineral Oil alone, 37 SUS. 47

Reduction, Percent of .0033 in Aluminum Alloy 1100 Rolling Load RollingLoad 5200 lbs. per 7500 lbs. per in. of Strip in. of Strip Width WidthComp. No. 4 52. 7 59. 2 4 parts Tallow Alehol, in Light Min. Oil,

37 SUS (Saybolt seconds, universal) 50.6 55. 5

Lubricants of our invention are more efiicient for rolling aluminumstrip than the commonly used fats or fatty acid esters in a number ofcases of rolling, using various gauge aluminum, various loads andvarious base oils, as the following Table 3 shows:

Comp. No. 3 Comp. No. Comp. No. Comp. No. Comp. No. 4 parts Palm Oil, inLight Min. Oil, 37 SUS 4 parts Butyl Stearate, in

Light Min. Oil, 37 SUS- 4 parts Lanolin, in Light Min. Oil, 37 SUS LightMin. Oil, 37 SUS, No

Additive Comp. No. 8 4 parts Palm Oil, in Light Min. Oil, 58 SUS 4 partsButyl Stearate, in

Light Min. Oil, 58 SUS '4 parts Lanolin, in Light Min. Oil, 58 SUS LightMin. Oil, alone, No

Additive For comparing a range of concentrations of our lubri- Theeffect of additions of polypropylene glycol to a fatty alcohol inimproving the lubricating properties is shown in the following Table 5,with reduction as a function of percent glycol, in a typical alcohol andglycol mixture. The total mixture was held constant at 4 parts by weightin a light mineral oil, 37 SUS at 100 F.

Table 5 Percent Polyprop. Reduction, Per- Glycol 150 in a cent, of .0033in. Mixture of Tallow Aluminum Alloy Alcohol and 1100, Rolling LoadPolyprop. Gly. 150 7800 lbs. per in. of

Strip Width A definite improving effect of glycol content is noted atthe initial addition level of 1.25%.

Some of the novel lubricant additive mixtures of our invention aresuperior also from the anneal stain point of 25 view. As mentionedpreviously, an excellent criterion of freedom from anneal stain is theboiling range of the material in question. Since the removal oflubricant from the aluminum sheet or foil during the heat treatingcycles is essentially a distillation process, we have used distil lationtests as a means of comparing their staining tendencant mixtures and acommercial product, we have chosen a typical ratio of alcohol to glycol,as described below. This has been compared to the same concentrations ofbutyl stearate, in a typical base oil, a light mineral oil,

viscosity 37 SUS at 100 F.

cies. We list below in Table 6 the temperatures at which the indicatedpercentages of materials were distilled and the quantity and type ofresidue, if any, which remained in the flask when distillation wascomplete. dues denote the relative staining quality at the final tem-These resi- Table 6 F.) Temperature of Liquid at Which Indicated Percentof Volume was Distiller. (Atm. Pressure) Composition Init. 10% 50% EndResidue B. P. Pt.

4 arts Coml. Lauryl Ale., 1 part 480 495 525 545 570 595 670 None.

Polyprop. Gly. 150. 3%itsllallowAlc lpart Polyprop. 503 532 593 626 649680 785 Do.

y. 50. Polyprop.Gly.150 464 468 491 527 536 545 549 Do. ButylStearate670 685 710 735 735 775 875 Moderatie1 Carbon and arms Palm Oil 750 775815 850 885 935 Very large amts. Carbon andResidue. Kerosene 390 400 410425 435 440 460 None. Light Min. Oil, 37 SUS 520 528 545 565 590 597 615Do.

Table 4 Reduction, Percent of .0033 in. Aluminum Alloy 1100, RollingLoad 6500 lbs. per Concentration in. of Strip Width of Additive in LightMin.

Oil, Mixture: 3 parts Tallow Alcohol; Butyl 1 part Polyprop. StearateGly.

peratures indicated. However, since much aluminum annealing is performedat temperatures below the final temperatures indicated in some cases,those materials with abnormally high end points on distillation would beunsatisfactory because of undistilled liquid residues which In thiswork, a neutral (natural gas) atmosphere was employed in line with thecommon practice in the industry. pheres had been employed, the resultswould have been different with, in most cases, more residues and higher70 final distillation temperatures.

Several comparisons can be drawn from these data. Since light mineraloils are invariably used, there would be no advantage in using anadditive having a lower boiling range than they exhibit. It is desirablethat the addi- 75 tive approach as closely as possible to the limitwhich 65 remain on the sheet surfaces.

It oxidizing atmosthese oils set so that higher anneal temperatures neednot be maintained simply to drive olf additives present on the finishedsheet. This i the fault from which fats and fatty esters suffer, as canbe seen. Their end points in distillation are so high that operators areforced to heat their product much above temperatures necessary to heattreat the aluminum. These practices, of course, are wasteful andexpensive of times and eflicient use of the furnaces.

According to our invention, the lubricant comprises an additivedissoived in a light petroleum oil or distillate having a viscositybetween 30 and 80 Saybolt seconds, universal, at 100 F., the additiveconstituting about 1 to 25%, by Weight, of the oil or distillate, theadditive being a mixture of hatty alcohols of the general formula ROH,Where R is a straight parafinic chain of from 10 to carbon atoms, eithersaturated or partially unsaturated, and polypropylene glycol having anaverage molecular Weight between 134 and 4000, the polypropylene glycolamounting to about 1 to 75%, by weight, of the additive.

The invention is not limited to the preferred embodiment but may beotherwise embodied or practiced Within the scope of the followingclaims.

We claim:

1. A metal working lubricant consisting essentially of an additivedissolved in a light petroleum oil having a viscosity between and 80Saybolt seconds, universal, at 100 F., the additive constituting about 1to 25%, by weight, of the oil, the additive being a mixture of fattyalcohols of the general formula ROH, where R is a stnai-ght panaifinicchain of from 10 to 20 carbon atoms with not more than one double bond,and polypropylene glycol having an average molecular weight between 134and 4000, the polypropylene glycol amounting to about 1 to 75%, byWeight, of the additive.

2. An additive for light petroleum oils and distillates to improve theirlubricating properties, said additive consisting essentially of anihiture of fatty alchols of the genernal formula ROH, where R is astraight parafiinic chain of from 10 to 20 canbon atoms with not morethan one double bond, and polypropylene glycol having an averagemolecular weight between 134 and 4000, the polypropylene glycol amountto about 1 to by weight, of the additive.

3. A metal working lubricant consisting essentially of an additivedissolved in a light petroleum oil having a viscosity between 30 andSaybolt seconds, universal, at F., the additive constituting about 1 to25%, by weight, of the oil, the additive being a mixture of fattyalcohols of the general formula ROH, Where R is a straight paraflinicchain of from 10 to 20 carbon atoms with no double bonds, andpolypropylene glycol having an average molecular weight bet-ween 134 and4000, the polypropylene glycol amounting to about 1 to 75 by weight, ofthe additive.

4. An additive for light petroleum oils and distillates to improve theirlubricating proper-ties, said additive consisting essentially orf amixture of fatty alcohols of the general formula ROH, where R is astraight paraffinic chain of from 10 to 20 carbon atomswith no doublebonds, and polypropylene glycol having an average molecular Weightbetween. 134 and 4000, the polypropylene glycol amounting to about 1 to75 by weight, of the addtiive.

References Cited in the file of this patent UNITED STATES PATENTS JahnJuly 29, 1952 OTHER REFERENCES

1. A METAL WORKING LUBRICANT CONSISTING ESSENTIALLY OF AN ADDITIVEDISSOLVED IN A LIGHT PETROLEUM OIL HAVING A VISCOSITY BETWEEN 30 AND 80SAYBOLT SECONDS, UNIVERSAL, AT 100*F., THE ADDITIVE CONSTITUTING ABOUT 1TO 25%, BY WEIGHT, OF THE OIL, THE ADDITIVE BEING A MIXTURE OF FATTYALCOHOLS OF THE GENERAL FORMULA R-OH, WHERE R IS A STRAIGHT PARAFFNICCHAIN OF FROM 10 TO 20 CARBON ATOMS WITH NOT MORE THAN ONE DOUBLE BOND,AND POLYPROPYLENE GLYCOL HAVING AN AVERAGE MOLECULAR WEIGHT BETWEEN 134AND 4000, THE POLYPROPYLENE GLYCOL AMOUNTING TO ABOUT 1 TO 75%, BYWEIGHT, OF THE ADDITIVE.